Exodus 12:22

Hyssop. The Biblical hyssop, most authorities agree, is the gray-green marjoram, Origanum mam, now known in Palestine as za‘tar. This little plant with a pungent, fragrant smell, a taste something like peppermint, and masses of tiny white flowers, grows commonly on rocks and terrace walls. It has thick, hairy leaves and branches well adapted to holding liquids. It is used today as a spice or condiment and has some repute as a medicine. The Samaritans still use a bunch of za‘tar at their Passover ceremonies to smear the blood of the paschal lamb upon the door frames of their houses.

In addition to its use in the Passover ritual, hyssop was employed on the day of the cleansing of a leper or a house (Lev. 14:6, 49), or one defiled by the dead, in connection with the offering of the red heifer (Num. 19:6, 17). Moreover, Moses used hyssop when he “sprinkled both the book, and all the people” at the ratification of the covenant (Heb. 9:19). Hyssop thus became symbolic of cleansing (Ps. 51:7). See also on v. 7.

None of you shall go out. In this night of judgment there would be no safety anywhere except behind the bloodstained door. As for the Hebrew there was no assurance of safety beyond the protection of the blood of the lamb, so for the Christian there is no other salvation than the blood of Jesus Christ, the true “Lamb of God” (John 1:36; Acts 4:12).